Outline

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T= Monitoring Faults

1. Devices that Monitor Faults

• geologists invented instruments to observe faults that
  • measure stress/ deformation in crust

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* creep meter

• measures horizontal movement of the ground
• laser-ranging device
  • uses laser beam to detect tiny fault movement
• tiltmeter

*
** measures tilting of ground

• Satellite Monitor
  • uses satellite with radar to make images of faults

1. Monitoring Risk in the United States

• geologists can't predict when/ where earthquake will strike
  • usually stress along fault increases until earthquake occurs
    • sometimes earthquake doesn't occur
    • earthquake may relieve stress along a another part of a fault
• geologists know
  • earthquakes are likely wherever plate movement stores energy in the rock along faults
• geologist can determine earthquake risk
  • where faults are active
  • where past earthquakes have occurred
• In the United States
  • risk is highest along Pacific coast

• California, Washington, Alaska

Diagram

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A diagram of how a laser ranging device works